Mobile computers, including handheld devices, data collection devices and vehicle mount computers are used in an increasingly wide range of applications and environments. In some environments, the mobile computers can be exposed to rapid transitions in temperature and humidity ranging from (−30° C. to +60° C.) and anywhere from (10% to 100%) in relative humidity. This has a direct impact on the performance of mobile computing devices and can cause fogging and/or frosting of display windows, scanner/imager exit windows and keypad freezing, which prevents use of the devices and a build-up of moisture internal to the devices which can lead to component failure and/or corrosion. The problem can be especially acute in the area of devices for “cold” supply chain logistics (SCL) which are subject to repeated and rapid changes in temperature where, for example, the device may be repeatedly moved between sub-zero, dry environments (such as refrigerated warehouses) and hot, damp environments (such as loading docks, etc.).